Currently, post spacers (PS in abbreviation) on a color filter substrate are generally classified into two categories, a main post spacer (Main PS) functioning as a main support and a sub post spacer (Sub PS) functioning as an auxiliary support, and the Main PS and the Sub PS are required to have a certain height difference therebetween.
In the prior art, in order to achieve the certain height difference between the Main PS and the Sub PS, the Main PS is generally provided on the color filter substrate so that it can directly contacts a TFT on an array substrate after the color filter substrate and the array substrate are aligned and assembled, and the Sub PS is provided in a region where a color filter on the color filter substrate and a black matrix overlap, so that a height difference occurs between the Main PS and the Sub PS. However, when the Main PS directly contacts the TFT, poor contact of the TFT is readily caused and the Sub PS is apt to tilt, which will affect the product quality. Alternatively, in a patterning process for manufacturing the post spacers, a gray tone mask plate or a halftone mask plate is used for exposing a post spacer layer, wherein the Sub PS corresponds to a light semi-transmissive region of the gray tone mask plate or the halftone mask plate, the Main PS corresponds to a light transmissive region of the gray tone mask plate or the halftone mask plate, and the remaining parts correspond to light non-transmissive regions of the gray tone mask plate or the halftone mask plate, and then the post spacer layer are developed to obtain the Main PS and the Sub PS. Through the above patterning process, the height difference between the Main PS and the Sub PS can be obtained. However, the patterning process using the gray tone mask plate or the halftone mask plate is high in cost and it is difficult to meet requirements on cost savings and improved production capacity.